Michigan officials are asking the public to check trees and report signs of the invasive Asian longhorned beetle.
August is Tree Check Month, according to the Department of Agriculture’s Animal and Plant Health Inspection Service, as it is the most likely time to see the Asian longhorned beetle and the damage it causes to trees.
Even though sightings of the Asian longhorned beetle are uncommon, people can still look for signs of the beetle by checking trees on their property and in their community for damage.
What is an Asian longhorned beetle?
The Asian longhorned beetle is a non-native, wood-boring beetle that’s considered invasive in North America, as it attacks more than 12 types of hardwood trees, including maples, elms, horse chestnuts, burches and willows.
There are no effective predators or diseases in North America to keep the Asian longhorned beetle populations in check.
Adult female Asian longhorned beetle will chew a small depression in tree bark to deposit each of her up to 90 eggs. After the eggs hatch, the larvae will eat their way into the tree’s heartwood, leaving tunnels that damage the tree.
By August the next summer, the beetles would bore round exit holes and emerge as adults to mate and start the cycle again.
What happens to infested trees?
According to the Michigan DNR, infested trees do not recover and will die. This can make trees become safety hazards as branches could drop and trees could fall over, especially during storms.
Since many types of trees could be affected and infestation is fatal, managing the beetle means removing both the infested and at-risk trees.
How to identify
An adult Asian longhorned beetle has a shiny, black body with white spots. Its body is about 1 to 1.5 inches long. It also has black-and-white antennae longer than its body, six legs, and feet that can appear bluish.
The white-spotted pine sawyer, a Michigan native, resembles the Asian longhorned beetle. However, the pine sawyer is brown to black, not shiny, and has a telltale white spot between its head and the top of its wing covers.
Signs of infestation
Here are the signs that a tree could be infested, according to the Michigan DNR:
- Round exit holes about the diameter of a pencil found in tree trunks and branches.
- Shallow, oval or round scars in the bark, where the adult beetle chewed an egg-laying site.
- Material that looks like wood shavings lying on the ground around the tree or in the branches.
- Dead branches or limbs falling from an otherwise healthy-looking tree.
Don’t move firewood
While the Asian longhorned beetle doesn’t move far on its own, it can hitchhike to a new area through untreated firewood. When traveling, the Michigan DNR recommends leaving firewood at home and buying locally or choosing certified, heat-treated firewood to prevent the beetle from spreading to new places.
How to report
If you see an Asian longhorned beetle or tree damage, report it to the ALB hotline at 866-702-9938 or submit an online report through the ALB webpage. You can take a photo of the beetle or the tree damage, or try to capture the beetle in a container and freeze it to preserve it for identification.
USDA and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service are trying to eliminate the Asian longhorned beetle from the U.S. The ALB program has eradicated infestations in Illinois; Boston, Mass.; New Jersey, Brooklyn, Queens, Manhattan, Staten Island and Islip in New York; and a portion of East Fork State Park and Stonelick and Monroe townships in Ohio. Officials are continuing to work in other infested areas of Massachusetts, New York, Ohio and South Carolina.